ENVIRONMENTAL CONTROL SYSTEMS

An aircraft propulsion system (20) includes a gas turbine engine; an environmental control system (ECS) (22); and a bleed flowpath (600) from the gas turbine engine through the ECS (22). A turbine (28) is along the bleed flowpath (600) and a propulsion fan (26) is mechanically coupled to the turbine (28) to be driven by the turbine (28).